Field of the Invention
The present invention relates to a display device integrated with a touch sensor.
Discussion of the Related Art
In recent years, various flat panel display devices have been developed to meet the needs for appropriately displaying various types of multi-media. The development of flat panel display devices has been directed to achieving large screen, low manufacturing costs, and high qualities such as displaying moving images of high quality, high resolution, high brightness, high contrast ratio, and wide color reproduction range. Also, various input devices, such as a keyboard, a mouse, a track ball, a joystick, and a digitizer, have been used to allow a user to interface with flat panel display devices.
However, the user may become dissatisfied due to the need to learn how to use various types of input devices. Furthermore, these input devices occupy physical space. Thus, there has been an increased demand for a convenient and simple input device capable of reducing erroneous operations. In response to such a demand, a touch sensor has been proposed to enable the user to input desired information by directly touching a screen, or by approaching the screen with his or her hand or a pen while the user watches the display device.
The touch sensor may have a simple configuration capable of reducing erroneous operations. The user may be able to perform an input action without using a separate input device, and can quickly and easily operate the display device using the touch sensor while watching the contents displayed on the screen. Thus, such a touch sensor has been applied to various types of display devices.
Touch sensors may be classified into an add-on type touch sensor, an on-cell type touch sensor, and an integrated type (also referred to as in-cell type) touch sensor, depending on their structures. The add-on type touch sensor may be configured such that a display device and a touch panel including a touch sensor are individually manufactured, and then the touch panel may be attached to an upper substrate of the display device. The on-cell type touch sensor may be configured such that the touch sensor may be directly formed on the surface of an upper glass substrate of the display device. The integrated type touch sensor may be configured such that the touch sensor may be formed inside the display device to thereby achieve thin profile and increase durability of the display device.
The integrated type touch sensor has such advantages of thin profile and improved durability, because typically, the common electrodes of the display device also serve as the touch electrodes of the touch sensor. Due to these advantages over the add-on type and on-cell type touch sensors, the integrated type touch sensor has been recent focus of interest in display industry.
The integrated type touch sensor may be divided into an optical touch sensor and a capacitive touch sensor, depending on the method of sensing a touched portion. The capacitive touch sensor may be further divided into a self-capacitive touch sensor and a mutual capacitive touch sensor.
The self-capacitive touch sensor may have a plurality of independent patterns in a touch area of a touch sensing panel, and measure changes in capacitance of each independent pattern, thereby detecting whether or not a touch operation is performed. On the other hand, the mutual capacitive touch sensor may have X-axis direction electrode strings (for example, driving electrode strings) and Y-axis direction electrode strings (for example, sensing electrode strings) which cross each other in the touch area of the touch sensing panel in matrix, apply a driving pulse to the X-axis electrode strings, and sense changes in voltages generated in sensing nodes defined as the crossings of the X-axis direction electrode strings and the Y-axis direction electrode strings through the Y-axis direction electrode strings, thereby detecting whether or not a touch operation is performed.
However, in the mutual capacitive touch sensor, a mutual capacitance between the X-axis direction electrode strings and the Y-axis direction electrode strings is small, but parasitic capacitance generated in the X-axis direction electrode strings and the Y-axis direction electrode strings by the data lines and the gate lines arranged in the display device is large. As a result, it may be difficult to detect with precision touched positions.
Also, the mutual capacitive touch sensor has a complicated construction of routing wires, because touch driving routing wires are connected to touch driving electrode strings (for example, the X-axis direction electrode strings) and because touch sensing routing wires are connected to touch sensing electrode strings (for example, the Y-axis direction electrode strings) for multi-touch operation.
For these reasons, the self-capacitive touch sensor, which has a simple construction of routing wires and high touch sensibility, has been widely used.
Hereinafter, a display device integrated with a self-capacitive touch sensor (hereinafter, simply referred to as “touch sensor integrated type display device”) according to the related art will be described with reference to FIG. 1. The display device may be a liquid crystal display device, although it may also be an organic light emitting display device or other types of display devices.
FIG. 1 is a planar view illustrating a touch sensor integrated type liquid crystal display according to the related art.
As illustrated in FIG. 1, the touch sensor integrated display device includes an active area AA, in which touch/common electrodes are arranged and data are displayed, and a bezel area BA outside the active area AA. The bezel area BA has various wires including routing wires for driving and sensing touch electrodes and an integrated circuit (10) for driving a source driver.
The active area AA includes a plurality of touch/common electrodes Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, Tx41 to Tx44 and Tx51 to Tx54, and a plurality of routing wires TW11 to TW14, TW 21 to TW24, TW31 to TW34, TW 41 to TW44 and TW51 to TW54 connected to the plurality of touch/common electrodes Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, Tx41 to Tx44 and Tx51 to Tx54, respectively. The plurality of touch/common electrodes Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, Tx41 to Tx44 and Tx51 to Tx54 are divided in a first direction (e.g., x-axis direction) and a second direction (e.g., y-axis direction) which cross to each other. The plurality of routing wires TW11 to TW14, TW 21 to TW24, TW31 to TW34, TW 41 to TW44 and TW51 to TW54 are arranged in parallel to each other along the second direction.
The plurality of touch/common electrodes Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, Tx41 to Tx44 and Tx51 are formed by dividing common electrodes of the display device. The plurality of touch/common electrodes Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, Tx41 to Tx44 and Tx51 may function as common electrodes during a display mode for displaying image data, and function as touch electrodes during a touch mode for detecting touch locations.
The integrated circuit 10 in the bezel area BA supplies image data to data lines in synchronization with driving of gate lines (not shown) of the display, and supplies a common voltage to the touch/common electrodes Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, Tx41 to Tx44 and Tx51 during the display mode. Also, the integrated circuit 10 supplies a touch driving voltage to the touch/common electrodes Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, Tx41 to Tx44 and Tx51 to Tx54 during the touch mode, and detects a touch location by scanning changes of touch/common electrodes before and after the touch is performed.
The touch sensor integrated display device includes various wires, for example, the routing wires TW11 to TW14, TW 21 to TW24, TW31 to TW34, TW 41 to TW44 and TW51 to TW54 and the data lines (not shown) extended from the active area AA and connected to the integrated circuit 10.
The routing wires TW11 to TW14, TW 21 to TW24, TW31 to TW34, TW 41 to TW44 and TW51 to TW54 are connected to the touch/common electrodes Tx11 to Tx14, Tx21 to Tx24, Tx31 to Tx34, Tx41 to Tx44 and Tx51 to Tx54 on a one-to-one basis. As a result, as the size of the touch sensor integrated type display device increases, the number of the routing wires also increases, because each of the routing wires is connected to each of the touch/common electrodes.
For example, when a touch sensor integrated type display device having a size of 15.6 inch is constructed with one touch/common electrode on a pitch size of 4.3 mm×4.3 mm, the touch, 80 touch electrodes are arranged in the x-axis direction and 45 common electrodes are arranged in the y-axis direction, resulting in a total number of touch/common electrodes of 3,600. In such a case, the 3,600 touch/common electrodes are connected to the integrated circuit 10 through 3,600 routing wires. The routing wires have to be arranged to overlap the data lines to prevent reduction of the aperture ratio of the display device.
Thus, when the routing wires are arranged in only one direction, the size of the touch/common electrodes should be enlarged or there may be an occasion where some of touch/common electrodes are not connected to the routing wires, thereby to reduce touch sensibility.